1. Field of the Invention
This invention relates generally to portable stereo sound sets, such as a set that includes a cassette stereo tape player and a stereo FM radio, and more particularly to a set of this type to be worn by a dancer who listens to music through stereo earphones mounted on his head, the earphones being each provided with an attitude-sensitive device functioning to vary the volume of sound heard in the earphone so as to coordinate the sound volume with the dancer's movements as reflected in the changing attitude of the dancer's head.
2. Status of Prior Art
In a stereo sound system, whether an FM radio or a stereo record player, the audio signals are fed into two independent audio amplifier channels, each terminating in a loudspeaker or earphone. This system functions to give the listener an aural perspective similar to that he would receive at the original sound source.
Portable stereo cassette tape player/radio sets, such as the well-known SONY WALKMAN are now widely available. These sets are adapted to be clipped onto or otherwise worn or carried by an individual who listens to broadcast or tape recorded stereo music through left and right earphones mounted on his head. A stereo set of this type includes binaural amplifier channels, each being provided with an amplitude-control stage to adjust the base level of the volume of sound heard in the related earphone.
Individuals equipped with such portable stereo sound sets often dance as they listen to the music, just as they would when hearing music in a night club or disco. It is not an uncommon street sight to see an adolescent carrying a portable stereo sound set and wearing stereo earphones on his head, gyrating to rock music that he alone can hear. This activity is also carried out by many individuals in the privacy of their homes.
When in a night club or disco an individual dances to the music being played, his movements are reflected in the attitude of his head, particularly in dancing to rock music. Thus as he dances, his head will tilt from side to side or incline in the forward or reverse direction in keeping with the tempo of the music, thereby translating, as it were, musical expression into body language.
When a dancer throws his head to one side, the music as heard in the ear that is then up becomes somewhat louder than that heard in the ear that is then down. While this difference in volume is not pronounced, the human ear is highly sensitive to such changes. Changes in volume of sound heard by both ears also occur when the head is thrown back or thrust forward. In that case, the volume in both ears is at the same level, but this volume rises and falls depending on the inclination of the head.
With a changing head orientation or attitude relative to the sound source, the volume of the sound in both ears may be increased or decreased to the same degree, or the volume of sound heard in one ear relative to that in the other ear may go up or down. Hence even though in a night club or a disco, it is recorded rather than live music that is being heard by a dancer, the dancer nevertheless experiences through his ears an apparent coordination of the pulse and expressive content of the dance music with his own movements.
The importance of this interaction can best be explained by analogy. When a company of dancers performs on a stage accompanied by a live orchestra whose conductor observes the dancers, the conductor will coordinate the performance of the musicians under his control with those of the dancers. Thus a conductor who senses that the beat of the music may be too fast for the dancers to follow will slow down the beat to accommodate the dancers. And when the dance activity his highly vigorous, the conductor will raise the volume of the music to accompany this activity and thereby intensify the impact of the performance on the audience.
But this is not a one-way street, for in dancing to music, dancer seeks to express in movement the tempo and expressive content of the music. Hence there is a dynamic interaction between the music being performed and the dancer's movements. But if a dancer performs to recorded music, there can be no such interplay, for the reproduction of the recorded music is altogether independent of the dancer's movements.
A similar situation exists for a dancer who is hearing dance music through stereo headphones, for there is no coordination between the dance music and the dancer's movements. The reason for such lack of coordination is that what the dancer hears through earphones mounted on his head is at a pre-adjusted volume level that is independent of the attitude of the head. Regardless of how the dancer changes his head orientation in keeping with the pulse of the music, the volume level of the music remains unchanged. As a consequence, the dancer is deprived of the interactive experience between movement and dance and the emotional rewards which accompany this experience.
Because the present invention makes use of attitude-sensitive potentiometers which are attached to the earphones, the following patents, through unrelated to stereo sound systems, are nevertheless pertinent, for they disclose in another context attitude-sensitive potentiometers.
The Cantarella et al. U.S. Pat. Nos. 4,167,818 and 4,244,177 disclose an electronic inclination gauge or level to determine the degree to which a surface is inclined with respect to a vertical or horizontal plane, use being made of a gravity-sensing potentiometer.